Topic: CB750A - EFI project

[cfeste]

Hi!

Thought I would present my project, since I may have a few (or maybe many) questions later on 

I bought a bit of a dog a couple years ago. A 1977 hondamatic, with low to no compression, messed up carbs etc. And having converted a 78 Porsche 911 to EFI, I want to do the same to the bike.

Here is what I have sourced so far:

Microsquirt ECU
GSXR600 throttle bodies (2001-2003)
GSXR750 fuel rail (It is modular, so I can make longer pipes to match up with factory intake boots just using f.ex. silicon reducers or some other form of adapter between).
Innovate LC1 wide band o2 sensor

I am also planning on making it an 836 or 849 cc, and putting on a 41 or 41A cam and a new exhaust from Cyclexchange. I would like to avoid making it so "big" that I need to modify any internal stuff in the engine.

Later on, I also hope to do the ignition, something like EDIS if possible since it is such a well travelled route.

My biggest issue right now seems to be deciding what to do about fuel pump and fuel return. I am looking into cutting out the in-tank fuel pump from a GSXR600 (Seen it done in another thread I believe), as it seems to be the least complicated thing since that pump has the fuel regulator and return built in.

Feel free to chip in with any thoughts or ideas!

[dusterdude]

Sounds neat,im gonna follow this

[Retro Rocket]

Hi!

Thought I would present my project, since I may have a few (or maybe many) questions later on 

I bought a bit of a dog a couple years ago. A 1977 hondamatic, with low to no compression, messed up carbs etc. And having converted a 78 Porsche 911 to EFI, I want to do the same to the bike.

Here is what I have sourced so far:

Microsquirt ECU
GSXR600 throttle bodies (2001-2003)
GSXR750 fuel rail (It is modular, so I can make longer pipes to match up with factory intake boots just using f.ex. silicon reducers or some other form of adapter between).
Innovate LC1 wide band o2 sensor

I am also planning on making it an 836 or 849 cc, and putting on a 41 or 41A cam and a new exhaust from Cyclexchange. I would like to avoid making it so "big" that I need to modify any internal stuff in the engine.

Later on, I also hope to do the ignition, something like EDIS if possible since it is such a well travelled route.

My biggest issue right now seems to be deciding what to do about fuel pump and fuel return. I am looking into cutting out the in-tank fuel pump from a GSXR600 (Seen it done in another thread I believe), as it seems to be the least complicated thing since that pump has the fuel regulator and return built in.

Feel free to chip in with any thoughts or ideas!

Hi Mate and welcome. I'll be doing the very same thing in the future, I already have the TB's sorted out {GSXR600 2002}so they are a direct bolt on with honda compatible throttle set up.  There are fuel pumps available that don't need submerging, I think some of the R6's have external fuel pumps, a lot of the quads have them as well, I'm just having another small tube brazed into the bottom of the tank for a return, pretty simple to do. Mines going into a billet block 1000cc build eventually...

Here's my throttle bodies...

[cfeste]

Nice fuel rail!

What have you been planning to use to make the TB's connect with the inlets, since they are a bit offset in comparison? I was planning on having the TB's respaced by using the modular fuel rail from a 750 with some custom pipes in between.

Also like your idea about the fuel return. Clean and simple. Have read about a very low watt consuming fuel pump from a quad bike which is on my list of options.

[Retro Rocket]

Nice fuel rail!

What have you been planning to use to make the TB's connect with the inlets, since they are a bit offset in comparison? I was planning on having the TB's respaced by using the modular fuel rail from a 750 with some custom pipes in between.

Also like your idea about the fuel return. Clean and simple. Have read about a very low watt consuming fuel pump from a quad bike which is on my list of options.

Mine TB's aren't offset, they have been reracked to fit Honda spacing, as well as a new throttle linkage fitted in the center,  so stock cables can be used. I'll use the larger diameter F2/F3 750 manifolds. I plan on using an external pump and will house it next to the battery, I'm also going to use a modern smaller battery and completely different wiring {digital fuse box} , so I have plenty of room under the seat, I may route a duct under the tank to supply cool air to the pump so it doesn't get hot sitting next to the battery... Its still in the planning stages but it will be done properly... I'm quite OCD about doing things correctly, albeit slowly ...

[cfeste]

Right, I see that now! Curious to know which fuel pump you end up with - I'm considering one from a LTR450, which apparently is quite small and use less watts then most others.

http://74.124.198.224/~micro/viewtopic.php?f=29&t=23490

Quite interesting, since the actual pump seems to be inside a casing filled with fuel, so it cools the pump.

[Retro Rocket]

Right, I see that now! Curious to know which fuel pump you end up with - I'm considering one from a LTR450, which apparently is quite small and use less watts then most others.

I'm not to concerned with power draw, I'm using a completely different charging system with double the power, LED lights will help also...
Yes, its a money pit... {but i don't care}   

[cfeste]

Nice! I'm not sure it's as easy to make charging that much better on a Hondamatic, but I'm looking into that + LED lights.

[Retro Rocket]

Nice! I'm not sure it's as easy to make charging that much better on a Hondamatic, but I'm looking into that + LED lights.

There's a forum member that makes an upgraded charging system, its completely different to the permanent magnet type we have as stock, If I find the thread i'll link it here, also, the guy that did my fuel rail is a member too, let me know if you are interested and i'll post a link to his thread here....

Upgraded charging system...

http://forums.sohc4.net/index.php?topic=117735.0

[cfeste]

Good stuff!

[Bokeh]

I just bought the last Charging Upgrade that Anders had for the 750.  Sorry!  I sent him my Starter gear last week to modify.  About two weeks ago I asked him if he would be making anymore as I have another Matic I will be rebuilding and he said that he may be fabbing some more this spring.  If enough people were interested ya never know maybe he will make some more sooner.  Thought I would mention it as if you were interested it's about $640 including shipping.  You would need to provide the big starting gear right behind the flywheel and it needs to be in good shape.  A lot of people hammer them on and distort the metal.  But I would reach out as soon as possible to get on a list for the next ones he makes.

[cfeste]

Yeah, I might do that, but was thinking I would get it running, minimize amp use wit LEDs etc, and see if it holds up.

Anyone with experience in controlling ignition with Micro/Megasquirt? I was doing EDIS on the car, but it seems the Microsquirt can control the coils directly (Trigger wheel --> MS --> coils), so this seems like the best way to go (And less amp-consuming?). But of course, doing fuel first, then ignition when it runs well with the EFI.

[Retro Rocket]

Here you go, lots of reading here...   Justin, the guy in the second link, is the guy that built my TB's...

http://forums.sohc4.net/index.php?topic=30624.0

http://forums.sohc4.net/index.php?topic=80629.0

[cfeste]

Thanks!

Came across this on the microsquirt forum:

http://www.madhu.com/content/Main/FuelPumpController

Controls fuel pressure electronically by controlling the pump itself, and removes the need for a fuel return. Neat, and could save me some amps!

[Retro Rocket]

Thanks!

Came across this on the microsquirt forum:

http://www.madhu.com/content/Main/FuelPumpController

Controls fuel pressure electronically by controlling the pump itself, and removes the need for a fuel return. Neat, and could save me some amps!

Nice, thanks. it also looks like the LTR450 pump is good for this application, 2 amp max draw...
After a quick search it seems that the Honda 2008 trx 700xx uses the same pump at nearly a third of the price...$100 dollars, around $280 for the LTR pump..  This is the part number for the Honda pump...  16700-HP5-602..

Heres one for $90

http://www.ebay.com/itm/NEW-GENUINE-OEM-08-09-HONDA-TRX700XX-TRX-700XX-FUEL-PUMP-16700-HP5-602-/181654063212?pt=Motors_ATV_Parts_Accessories&hash=item2a4b6d086c&vxp=mtr

[chewbacca5000]

Hey Retro,

What are the main benefits from going EFI?  I can't imagine you will get a tremendous HP gain.  What about throttle response?

How much is this whole project going to cost?  I might be interested in EFI down the road.

[cfeste]

Fuel injection itself probably does not give very much HP gain. At least in the car, the HP gain comes more from controlling the ignition with the computer, which transforms the engine a lot. Smoother running etc. The other gains I get will be from displacement, cam and exhaust, all of which also benefits from the extra fuel and air the EFI can give compared to stock Hondamatic carbs. Could have done the same with bigger carbs I guess.

I am mildly concerned about throttle response. However, if a GSXR600 can have good throttle response with the same setup, why should I not be able to achieve it on a CB to some extent?

EFI is more for fun. I like projects, I like mixing old style with new technology. Plus, I am a computer guy 

I would have had costs fixing the carbs too. And the EFI will not need maintenance the way carbs will. And I hate the thought of the old school carb tuning, which I would not have the patience for to do right. Also, this EFI setup will potentially allow for a lot more and bigger mods than I am doing at this point.

If you look up the price for the GSXR parts, Microsquirt, o2 sensor (cheaper ones exist), fuel pump etc, you have a basic idea for EFI costs. I have been getting the parts over some time, and have avoided adding the costs toghether....

Geez, I paid more for a used LTR450 pump than for a new Honda pump!! Thought I had done the research...

[cfeste]

These projects will soon end up with a pre-compiled list of the best parts, and it would make an awesome kit if someone would make the few custom items you need, + sell pre-programmed ECU's that just will need basic tuning to run optimal on each bike, and made instructions available. Look up bitzracing.com, this is the kit I put on the 911. One weekend, and I had it running with no issues other than minor tuning needed. Throttle response was one thing that needed some work.

[Retro Rocket]

Hey Retro,

What are the main benefits from going EFI?  I can't imagine you will get a tremendous HP gain.  What about throttle response?

How much is this whole project going to cost?  I might be interested in EFI down the road.

Cfeste answered most things, injection is more efficient, fuel mileage should be better under normal running, lighter throttle, as cfeste said, better response so better performance and cost, I'll have less in the injection than many here because i've taken my time and waited for most of the fettling to be done by others, I'm no expert on injection by any means and have learned lots here, I will have less in this than a set of high end mikuni's or keihin FCR's, but on the bike they are going on, cost doesn't concern me one little bit, i'm just putting together what I want...

Geez, I paid more for a used LTR450 pump than for a new Honda pump!! Thought I had done the research...

Cool find eh....

[cfeste]

Ordered CycleX 849 kit, their CX2 cam, HD bolts/nuts. Will probably need some valve parts etc, but will take a look at existing status first.

Anyone has or have heard of any recent experience with CycleX' "own" pistons? Read an old post by Hondaman where he said their 836 kit needed to be cleaned up a bit before installing.

Can't wait for spring! Norwegian winters make the non-heated, non-insulated garage a bit too cold to work in... Another summer project is to make the garage nice and cosy for next winter 

[chewbacca5000]

Ordered CycleX 849 kit, their CX2 cam, HD bolts/nuts. Will probably need some valve parts etc, but will take a look at existing status first.

Anyone has or have heard of any recent experience with CycleX' "own" pistons? Read an old post by Hondaman where he said their 836 kit needed to be cleaned up a bit before installing.

Can't wait for spring! Norwegian winters make the non-heated, non-insulated garage a bit too cold to work in... Another summer project is to make the garage nice and cosy for next winter 

I think most kits need to be cleaned up a bit to meet Hondaman's standards with the exception of the 1st to 4th oversize that z1enterprises once offered.  The $110 836 is a good bargain as well.

[Bokeh]

Just thought I would throw this in here.  This guy is selling 3 drag bikes.  Two of which are Matics.  He also has this listing near St. Louis for A Fuel injection kit for the CB750's.

https://stlouis.craigslist.org/mpo/4941855191.html

[cfeste]

No real excuse for being 3 years delayed here… But thought I would post a small update.

I had a guy weld adapters on to the intake ports with the correct angle and spacing to fit the GSXR600 throttle bodies. He also bored the cylinders and ported the top! It took a year, so there is one of the reasons for the delay. After that year it's all on me...



It needs a bit of grinding to look nice.

I plan on assembling the engine this winter, and maybe also get the frame ready.

Also: I am looking for a basic setup for the Microsquirt. Anyone got one they would be willing to share? Just looking for one that will get me started.

[Jerry Rxman Griffin aka MuthaF'er]

That's looking great. Bigger valves soon?

[cfeste]

The guy who did the porting and cleaned up the valves thought they would be fine, but I will consider it while I am putting things together. You think it would be a big benefit?

[Jerry Rxman Griffin aka MuthaF'er]

Yes. More air = more fuel = more HP.

[ratranger]

If you haven't settled on a fuel pump set up, you can do an intank one pretty small if needed.  I used a ninja650 regulator and a sportster 1200 pump with a home made sending unit.  It required a 1.55"×2.1" hole to be cut in the tank.  Holds steady at 41-43psi all the way to redline on my XS, no leaks, internally regulated, fits a tiny tank.  Just throwing it out there to show the possibilities.